title: The role of the drug-metabolizing enzymes.
abstract: Drug-metabolizing enzymes function in the biotransformation of both endogenous and exogenous lipophilic compounds. Phylogenetic studies indicate that the drug-metabolizing enzymes were a late evolutionary development. Stimuli for the evolution of these enzymes were probably movement to a terrestrial environment, a diet of higher plants and an increasing tissue specialization, with a consequential need for the formation and inactivation of hormones, bile salts etc. Most drug-metabolizing enzymes exist in multiple forms. Some are concerned solely with the metabolism of a very limited range of endogenous lipids; others such as 'phenobarbitone-type cytochrome P-450' seem to be concerned mainly wih the metabolism of exogenous compounds. In mammals the liver and intestine have a major role in the biotransformation of exogenous compounds, whereas in other tissues the primary function of the drug-metabolizing enzymes appears to be the metabolism of endogenous lipids such as steroids, lipid-soluble vitamins and fatty acids.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001711:Biotransformation; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004777:Environment; D004851:Epoxide Hydrolases / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000378:metabolism; D050356:Lipid Metabolism; D008862:Microsomes, Liver / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D010802:Phylogeny; D013045:Species Specificity; D013466:Sulfurtransferases / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D004364:Pharmaceutical Preparations; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D014453:Glucuronosyltransferase; D013466:Sulfurtransferases; D004851:Epoxide Hydrolases